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Color.A Property

Gets the alpha component value of this Color structure.

Namespace:  System.Drawing
Assembly:  System.Drawing (in System.Drawing.dll)

public byte A { get; }

Property Value

Type: System.Byte
The alpha component value of this Color.

The color of each pixel is represented as a 32-bit number: 8 bits each for alpha, red, green, and blue (ARGB). The alpha component specifies the transparency of the color: 0 is fully transparent, and 255 is fully opaque. Likewise, an A value of 255 represents an opaque color. An A value from 1 through 254 represents a semitransparent color. The color becomes more opaque as A approaches 255.

The following code example demonstrates the A, R, G, and B properties of a Color, and the Implicit member.

This example is designed to be used with a Windows Form. Paste the code into the form and call the ShowPropertiesOfSlateBlue method from the form's Paint event-handling method, passing e as PaintEventArgs.

private void ShowPropertiesOfSlateBlue(PaintEventArgs e)
{
    Color slateBlue = Color.FromName("SlateBlue");
    byte g = slateBlue.G;
    byte b = slateBlue.B;
    byte r = slateBlue.R;
    byte a = slateBlue.A;
    string text = String.Format("Slate Blue has these ARGB values: Alpha:{0}, " +
        "red:{1}, green: {2}, blue {3}", new object[]{a, r, g, b});
    e.Graphics.DrawString(text, 
        new Font(this.Font, FontStyle.Italic), 
        new SolidBrush(slateBlue), 
        new RectangleF(new PointF(0.0F, 0.0F), this.Size));
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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